MULTIMEDIA ALERT: A video interview with Dr. Camilleri is available for journalists to download on the Mayo Clinic News Network.

Irritable bowel syndrome is common, affecting 10 to 20 percent of the population in developed countries. IBS is not a disease, but rather a group of symptoms that occur together. The most common symptoms are cramping, abdominal pain, bloating, gas, diarrhea and constipation.

"Our goal is a better understanding of the mechanisms behind this syndrome. That way, we can foster individualized, specific treatment for patients with IBS," Dr. Camilleri says.

Why patients develop IBS is not clear. Psychological factors and genetic predisposition play a part in IBS, but Dr. Camilleri points to a variety of underlying irritants that disturb gastrointestinal functions and contribute to IBS symptoms. Examples include digesting certain food, prior gastroenteritis, the patient's gut flora, and bile acids and fatty acids (involved in digestion of food) arriving in the colon.

"If we can identify these irritants in the individual patient, we have the opportunity to prevent or reverse symptoms," Dr. Camilleri says.

IBS is typically diagnosed after a patient has recurrent abdominal pain or discomfort at least three days per month, in the previous three months, combined with a change in the frequency of bowel movements or a change in stool's appearance.

IBS can occur at any age, but often begins in the teens or early adulthood. It is twice as common in women as in men. Studies have shown that people who have a first-degree relative with IBS are at increased risk.

IBS may be a lifelong condition. For some people, symptoms are disabling and reduce the ability to work, travel and attend social events. Treatment often helps. Common treatments include fiber supplements, anti-diarrheal medications, eliminating high-gas foods, anticholinergic medications, antidepressants,antibiotics and counseling.